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DRV401：About Probe Excitation and Bandwidth

James Young
Prodigy 20 points
Part Number: DRV401
Other Parts Discussed in Thread: DRV421

Tool/software:

Hi E2E experts,

I am currently in the early stage of project research and component selection, but I have encountered some issues and look forward to your response.

I couldn't find the information in the datasheet about the bandwidth of the current signal that the DRV401 can measure. I assume this should be related to the frequency of the probe excitation, right?

The datasheet indicates that the probe excitation frequency is recommended to be between 250kHz and 550kHz. Given this, what is the supported measurement bandwidth?

To broaden the measurement bandwidth, is it possible to increase the excitation frequency significantly beyond 550kHz? What impact would this have? Would the measurement accuracy decrease?

Additionally, what is the general accuracy achievable when using the DRV401 for current measurement?

Looking forward for your reply. Thank you very much!

  • 0
    TI__Mastermind 32670 points

    Hello ??,

    James Young said:
    I couldn't find the information in the datasheet about the bandwidth of the current signal that the DRV401 can measure. I assume this should be related to the frequency of the probe excitation, right?

    This is not correct.  The device uses the probe excitation for lower frequencies and the higher frequencies are measured using the transformer effect from the compensation core.  This information is in the datasheet.  If the core can handle the higher frequency then the limitation will be the difference amplifier.

  • 0 in reply to Javier Contreras4
    Prodigy 20 points

    Thank you for your explanation. Following your advice, I checked the datasheet, which indeed clarified my doubts. Based on this, I have some new questions:

    1. The DRV401 uses different sensing principles at low and high frequencies. Will this affect the measurement accuracy? Is there a way for me to distinguish which sensing principle is dominant at the current frequency during use?


    2. At high frequencies, the accuracy mainly depends on the configuration of the mutual inductance coil and the precision of the differential amplifier. The configuration of the mutual inductance coil is something I need to consider. Is there a reference design available for achieving high-speed and high-accuracy signal measurements?

    Looking forward for your reply. Thank you very much!

  • +1 in reply to James Young
    TI__Mastermind 32670 points

    Hello,

    1) This document is for the DRV421 which is similar to the DRV401.  See section 2.1.8.  The DRV401 could operate at a different frequency as it depends on your probe design.  This will depend on your compensation core as well.

    2)This from what I have seen is all based on the material and the design of the compensation coil.  We do not have a design guide for this.

    Regards,

    Javier